We built a 17 X 21 ft addition about 18 months ago. It has a 16 in deep poured concrete footer with brick and block foundation. There are vents on 3 sides to code, 6 total. The inside of the dirt crawlspace is probably a bit below grade because of the excavation and the lot has a very gradual slope from back to front. We have gutters on the addition that drain all the way out to the street through a long buried black tube. Whenever it rains hard and long, water still pools in the dirt crawlspace and stays around for a week or so. After particularly heavy rain, you can see wetness climbing up the brick and block. In between rain the floor of the crawlspace remains pretty damp.
I am fairly certain that the water is not from roof/gutters. It is hard to believe that with ALL the roof runoff carried away that so much water still moves into the crawl. Looking at the inside of the crawl, it seems like the water is just kind of seeping through the foundation (or maybe under the foundation) and pooling. I know putting down 6 mil poly and installing a sump pump would help remove the pooling water and protect the floor system from dampness, but before doing that, I would like to know if there is something to be done to prevent so much water from entering the first place. What are my options here?
Any advice would be greatly appreciated.